Improve UI pref when sync/cancel account syncs.

The core of the change is in ManageAccountSettings#showSyncState(). New
code caches as much information as it can. And break out of loops as
early as possible.

Bug: 28575620
Test: make RunSettingsRoboTests
Change-Id: I076ce148e3d8db55f6cadfd9491f037f7a55a986

tests/robotests/src/com/android/settings/accounts/AccountPreferenceTest.java

@@ -0,0 +1,73 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.settings.accounts;
+
+import android.accounts.Account;
+import android.content.Context;
+
+import com.android.settings.R;
+import com.android.settings.SettingsRobolectricTestRunner;
+import com.android.settings.TestConfig;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.robolectric.annotation.Config;
+import org.robolectric.shadows.ShadowApplication;
+
+import java.util.ArrayList;
+
+import static org.mockito.Mockito.spy;
+import static org.mockito.Mockito.verify;
+
+@RunWith(SettingsRobolectricTestRunner.class)
+@Config(manifest = TestConfig.MANIFEST_PATH, sdk = TestConfig.SDK_VERSION)
+public class AccountPreferenceTest {
+
+    private Context mContext;
+    private Account mAccount;
+    private ArrayList<String> mAuthorities;
+    private AccountPreference mPreference;
+
+    @Before
+    public void setUp() {
+        mContext = ShadowApplication.getInstance().getApplicationContext();
+        mAccount = new Account("name", "type");
+        mAuthorities = new ArrayList<>();
+        mAuthorities.add("authority");
+
+        mPreference = spy(new AccountPreference(
+                mContext, mAccount, null /* icon */, mAuthorities, false /* showTypeIcon */));
+    }
+
+    @Test
+    public void setSyncStatus_differentStatus_shouldUpdate() {
+        mPreference.setSyncStatus(AccountPreference.SYNC_ERROR, true);
+        verify(mPreference).setSummary(R.string.sync_error);
+    }
+
+    @Test
+    public void setSyncStatus_sameStatus_shouldNotUpdate() {
+        // Set it once, should update summary
+        mPreference.setSyncStatus(AccountPreference.SYNC_ERROR, true);
+        verify(mPreference).setSummary(R.string.sync_error);
+
+        // Set it again, should not update summary
+        mPreference.setSyncStatus(AccountPreference.SYNC_ERROR, true);
+        verify(mPreference).setSummary(R.string.sync_error);
+    }
+}